Various methods for the polymerization of fluoropolymers in a nonaqueous medium of comprising liquid or supercritical carbon dioxide have been proposed. U.S. Pat. No. 5,496,901 discloses a processes for the making a variety of fluoropolymers comprising solubilizing a fluoromonomer in a solvent comprising carbon dioxide. PCT Publication No. WO 96/28477 discloses polymerization of a variety of fluoropolymers in a solvent comprising carbon dioxide while employing an initiator capable of producing stable end groups. These publications describe processes which work in laboratory scale reactors, e.g., 25-500 ml, when run in a batchwise fashion. In the Examples of these publications, the polymerization is run and then the reactor is vented and opened to recover the product. Such processes are not applicable to the commercial production of fluoropolymers where it is desired to recover product without having to disassemble the reactor.
Japanese Pat. Publication Kokai 6(1994)345824 discloses polymerizing TFE with fluorine-containing vinyl ethers in liquid carbon dioxide. A chemical initiator is used. Japanese Pat. Publication Kokoku 45(1970)3390 discloses the polymerization of either TFE or a TFE/olefin (hydrocarbon) copolymer in liquid carbon dioxide using irradiation with gamma rays to cause the polymerization. Continuous processes are mentioned in these references but only laboratory scale batch processes are illustrated in the examples.